This invention relates to a plug-in safety coupling for pressure pipes, such as for gases or fluids, comprising a pivotal blocking member. Couplings having pivotal blocking members have long been known. The coupling consists of a coupler box and a coupling plug, the coupler box constituting a housing within which a cylindrical blocking member is pivotally mounted. The cylindrical blocking member is diametrically penetrated by a bore. When the blocking member is pivoted within the coupler box such that its diametrical bore is no longer aligned, and in communication, with the pressure pipe, the flow is interrupted and the coupling plug may be plugged into the blocking member in a depressurized state, whereupon it is pivoted to the flow position along with the blocking member.
It must be ascertained that the conducting position is secured, which means that the coupling plug must be prevented from pivoting back with the blocking member. A plurality of alternatives are known for such securing. According to one alternative, the coupler housing, which encloses the blocking member and has a slot or oblong hole along the pivoting path of the plug, is specially shaped to secure the plug in the conducting position. The two inner edges of the arcuate oblong hole have a recess at the end of the oblong hole, i.e. in the conducting position of the plug, which recess is engaged by the plug due to the existing pressure by means of a shoulder formed on the plug. Therefore, the plug cannot pivot back unless it is previously pressed a short length into the blocking member against the pressure prevailing in the pipe so that its shoulder leaves the recess to permit pivoting. A disadvantage of this alternative resides in the fact that the plug must be pressed into the blocking member against the pressure within the pressure pipe, which is problematic for plugs of larger diameter and at higher pressure.
Another way of securing the conducting position of the plug comprises a sleeve which encloses the coupler housing at the rear side thereof and is easily axially movable on the coupler housing to the rear in the direction of the pressure pipe against the force of a spring. The front rim of the sleeve has two diametrically disposed cams projecting from the rim, the cams engaging bores or recesses in the cylindrical wall of the blocking member. The bores or recesses are so disposed that they are engaged by the cams in the conducting position of the blocking member. Provided are further bores or recesses which are engaged by the cams when the blocking member is pivoted to the coupling position. For engaging the safety coupling, the plug is first inserted into the blocking member. Then, the sleeve having the cams is withdrawn from the bores or recesses in the blocking member, whereupon the plug including the blocking member can be pivoted into the conducting position in which the cams of the spring-loaded plug again engage in correspondingly disposed bores or recesses on the blocking member to secure its pivoted position. For decoupling, the sleeve is withdrawn so that the blocking member is again set free to pivot.
A third alternative for blocking the pivotal blocking member in its various rotary positions is realised by a rotatable ring disposed on the rear side of the coupler box. This ring has a steep internal thread so that it is axially moved on the coupler box when the latter rotates. The periphery of the cylindrical blocking member has flat portions produced by milling, on which the front rim of the rotatable ring comes to lie when the ring is rotated on the coupler box so that it moves in the direction toward the plug. The rotatable ring may be spring-loaded by an internal spring so that it is held rotated in this direction and may be rotated back only against the force of this spring. It is only by such spring-loaded back rotation that the front rim may be caused to withdraw from the flat portion and enable the blocking member to pivot.
All above-mentioned ways of securing the blocking member in the conducting position, however, cannot ascertain that the coupler box is protected against intruding dirt or dust when decoupled. When the plug is not inserted in the blocking member, the open bore in the blocking member forms an aperture in which dirt or even small particles may enter. If this happens, the bore can be cleaned only with difficulty. If necessary, it must be jetted or washed and then dried by pressurised air in order to secure full tightness when a plug is inserted and a pressurised medium is to be conducted in a tight manner.
The above-mentioned ways of securing the pivoting member are also relatively expensive in manufacture and mounting. Moreover, their handling is not fully self-evident.
It is therefore the object of the present invention to provide a plug-in safety coupling for pressure pipes having a coupler box and a blocking member pivotally mounted therein, which coupling permits a structurally simple, elegant and easy to handle securing of the blocking member in its pivot position, in addition to preventing the ingression of dirt and dust when the plug is withdrawn.
This object is met by a plug-in safety coupling for pressure pipes comprising a coupler box pivotally mounted therein, the blocking member having a diametrical through bore in which a plug can be inserted in a depressurized state at an acute to right angle with respect to the conducting position and brought into the conducting position by pivoting the plug. A cap-like locking sleeve having a hemispherical front end is placed over the coupler box with the pivoting member. The hemispherical front end has a spherically extending oblong hole which extends from the center of the hemispherical end along a great circle on the hemispherical end. The cap-like locking sleeve is rotatably mounted on the coupler box and actuated by a spring so that its oblong hole extends at an angle with respect to the pivoting plane of the blocking member and the plug, and is rotatable against the force of the spring into the pivoting plane of the blocking member and the plug.
Additional features, which alone or in combination with any other feature(s), such as those listed above may comprise patentable subject matter and will become apparent to those skilled in the art upon consideration of the following detailed description of various embodiments exemplifying the best mode of carrying out the embodiments as presently perceived.